[84.04] Cracking the Shell of Shell-Type SNRs with Spatially-Resolved Spectroscopy

X-ray observations of thermally dominated young supernova
remnants such as Cassiopeia A, Kepler, and Tycho show
complex morphology. The color separations visible in any
energy-colored counts image of one of these remnants suggest
the different physics occurring in different regions, for
example, thermally emitting ejecta lobes and nonthermally
radiating outer shocks. However, there is considerable
physics which is still hidden: temperature variation,
ionisation states, true separation of line and continuum
emission, effects of interstellar (and perhaps
circumstellar) absorption, and the velocity of the ejecta.
Using the spectroscopic capability of the Chandra
Advanced CCD Imaging Spectrometer, we can literally map the
spectral features of remnants. We will briefly explain our
techniques using the Interactive Spectral Interpretation
System (ISIS) and the Chandra Interactive Analysis of
Observations software for reducing and analyzing the data to
produce high resolution (1'' to 5'') maps of the spectral
parameters of Cas A, Kepler, and Tycho. Our process is a
two-phase approach, and we will compare and contrast some of
the ``first'' and ``second'' generation analysis products
for these remnants. The first analysis phase consists of an
initial mapping using computationally simple models to
represent the major line and continuum features of the
remnant. In the second phase, we use the first set of maps
to identify and locate regions of interest to fit with
specialized models. For example, we have discovered that
anomalously high fit temperatures to the bremsstrahlung
model in the first map is a powerful indicator of regions
which are dominated by synchrotron emission. Fitting these
identified regions with the more appropriate synchrotron
model allows us to measure the rates of particle
acceleration in the shock fronts (see Allen et al., this
conference) and show that the rates approach the Bohm limit.
We will briefly present some of these synchrotron emission
results, as well as results for the velocity and structure
of the thermal emission in these young remnants. This work
is made possible in part by the NASA LTSA grant NAG5-9237.

The author(s) of this abstract have provided an email address
for comments about the abstract:
mikstage@space.mit.edu